Middlesbrough are lining up a move for Andre Amougou following Rhys Williams's injury blow.
The former Reading and Burnley man, who is a free agent, has already spent time training with Boro this summer, but they looked settled for defenders.
However, Tony Mowbray has now gone back for the Cameroon international after losing captain Williams to a serious ankle injury, which will likely keep him sidelined until 2013.
"Losing Rhys is not only a blow to him but to the club and the team," said Boro boss Mowbray.
"His versatility and athleticism and quality is something that we were dependent on this year a little bit, I think.
"We were hoping he was going to develop a really strong defensive relationship with Jonathan Woodgate.
"Anyway, he is out now and we have to take that on the chin. We have to make sure we aren't left short in a position of the pitch that is particularly crucial in this league.
"Andre is in, we will have a look at him for a day or two and make a decision.
"He is a very powerful centre-half, physically strong and we will know over the next day or so what we think.
"If ultimately he doesn't prove to be the one, we will look to the loan market, I would suggest, rather than think about buying a centre-half."
Meanwhile, Mowbray admits he is unlikely to be doing anything on deadline day, subject to a major departure.
"I don't think there'll be any more signings unless there's a substantial exit," he said.
"If anything dramatic happens and we had a massive bid for one of our players, we have a list of targets we would like to try to improve our squad.
"But if nothing happens, I don't think we'll be signing anyone."
Marvin Emnes has been the subject of interest from Swansea, but a deal now looks unlikely.
"A few weeks ago there were some enquiries but there's been nothing since then and I'm not anticipating any late calls with Marvin or any of our players," he said.
"Marvin's in the squad and will be travelling to Millwall with us and unless something happens you'll see him on the pitch, hopefully doing what he did last year and smashing one in."